AMD Athlon Could Slow Down Your Apple iPod

Apparently there is some sort of feature in the Mobile AMD Athlon which slows down the transfer speeds of your iPod.

If you bought an iPod to match your Mac – you’re in luck. Naturally, it just works out of the box. True plug-and-play. Hook it up to your FireWire port, charge it, store stuff on it. Grab it. Go mobile with it.

Unless, of course, you own an Athlon-powered notebook PC. This tale of woe from The Inquirer involves a Compaq Presario and its unfortunate owner.

The author found his Presario laptop didn’t have USB 2.0, only 1.1. So he duly purchased a CardBus USB 2.0 card, a USB->FireWire cable and a USB 2.0 hub to go with his shiny iPod.

Disaster struck. File transfers across USB 2.0 were slower than USB 1.1. Why? Why? Why?

He stumbled across some clues. Leaving screensavers running or moving the mouse a lot made it work better. Of course. But what was causing the problem?

Answer: the Athlon. Apparently it has something called ‘Power Now’ built into their Mobile+ 2400 CPUs. Something like Intel’s SpeedStep or the kind of power management built into every PowerPC processor since 1995’s 603e.

So the Athlon slows everything down when the PC’s not doing much. As the author says, “Unfortunately, USB2 drivers don’t count as “doing much”, so if nothing else is running, your CPU starts woefully underperforming. Since USB2 needs lots of CPU grunt, this cripples the speed of your transfer.”

Read more at IGM